Objective To observe the efficacy and safety of external use of Cold-Bi Formula and internal therapy of Bushen Zhuanggu Formula [Kidney-Supplementing Bone-Strengthening Formula（KSBSF） ] for ankylosing spondylitis（AS）.Methods Totally 216 cases of AS were randomized into the treatment group（101 cases

7 dropping） and control group（103 cases

5 dropping）.The treatment group was given KSBSF orally and externally applied Cold-Bi Formula topically.The control group was given KSBSF orally.Both groups were treated for 8 weeks.The Bath Ankylosing Spondylitis Functional Index（BASFI）

Bath Ankylosing Spondylitis Disease Activity Index（BASDAI）

spinal pain

TCM patterns score

finger-floor distance（FFD）

thoracic mobility

spinal mobility

Schober test

erythrocyte sedimentation rate（ESR） and C-reactive protein（CRP） were observed in both groups before and after treatment.The 20% response according to Ankylosing Spondylitis Assessments（ASAS20） was used to evaluate the clinical efficacy.Results The BASFI

BASDAI

spinal pain

TCM patterns score

FFD

thoracic mobility

spinal mobility

Schober test

ESR and CRP were improved in both groups after treatment（P<0.05）

especially BASFI

TCM patterns score

FFD

Schober test and spinal mobility in the treatment group（P<0.05 or P<0.01）.There were 89 cases（88.12%） and 73 cases（70.87%） reached ASAS20 in the treatment group and control group respectively after treatment

with a significant difference between groups（P<0.05）.Conclusion The efficacy of external and internal therapy of TCM for AS is superior to that of purely internal therapy of TCM.It can relieve the symptoms and signs and improve the TCM patterns score of AS patients.